Super Jet 62t vs 61x Not so braap

[Thomasbv]

Hey .. just bought a SuperJet sn, with newly restored engine, new pistons, new crank, new cylinder head ..
The setup is 701 61x engine, riva cylinder head, 2 x 46 mm Mikuni carburetor, Factory B-Pipe, but it does not feel as quick as my old 701 62t, with b-pipe, blowsion cylinder head, 2 x 38 mm carburator ..
There are almost no power in the bottom compared to the old 62t motor ..
Any ideas?

 

[jerzey]

I think the 46's are a bit much for your setup, I bet you some smaller carbs would get your throttle response back....

 

[Matt_E]

I doubt the carbs being rather large would cause it to have no bottom end power at all (unless they are Buckshot carbs lol). I would suspect they aren't tuned right.
Find out exactly which carbs they are, find out how they are jetted right now, then go to the carb jetting thread in the tech FAQ and find a comparable setup

 

[Bobert540]

X2 I have dual 46's on my 701. Check the tuning like Matt E suggested.

 

[Thomasbv]

its a dual Mikuni sbn 46mm will cheack the jets later..

but plugs has a nice light brown color, so think the jetting is okay..

Bobert540 : What size jets do you run, and what needle and seat? and your setup

But is the 61x engine as good as the 62t engine?

 

[Bobert540]

I am running Dual 46 Blackjacks on a 701 bored out to 84mm and ported so I don't think my jetting will help. The 61x/61x is still a great engine, the more desireable 62t/61x is great but you can still do a lot with the 61x platform. Special FX on here is running a XS865 ss and a DASA 850ss on 61x cases.

 

[Thomasbv]

120 and 100.. Both screws Are 1 round out..
theres is fuel pumps on both carburators If it make Any difference?

 

[Matt_E]

Are they both hooked up to their own pulse line?

 

[Thomasbv]

Are they both hooked up to their own pulse line?

Yes...

 

[Matt_E]

This motor has 61X cases, yes?
You might pull both pulse lines off the carbs, put your finger on the end, crank the engine and make sure you're getting a pulse signal on each line. I'm assuming that a second pulse fitting has been installed in the intake manifold. This isn't straight forward in 61X cases with dual carb manifolds. It's very possible that the second fitting has been installed blind and is getting blocked from getting a signal.

 

[Crab]

If it has lazy race porting it won't have any bottom end either...

 

[Thomasbv]

Yes 61x cases and cylinder.. It has an riva intake manifold, i Will try to test pulse signal.. If i only Got one working pulse line, Can i Then use a T "adapter" ?

 

[Crab]

Yes 61x cases and cylinder.. It has an riva intake manifold, i Will try to test pulse signal.. If i only Got one working pulse line, Can i Then use a T "adapter" ?

You need one for each fuel pump

 

[Thomasbv]

Okay But Do i need to have two fuel pumps on?

 

[Matt_E]

Yes you probably do.

 

[Thomasbv]

Yes you probably do.

How Do i fix That?

 

[Matt_E]

First, check if you have pulse signal on both lines.
If not, tee them together to the one you have signal on and try out the ski on the water.
If that fixed it, then take the intake manifold off and fix the problem with the second pulse fitting.

 

[Thomasbv]

First, check if you have pulse signal on both lines.
If not, tee them together to the one you have signal on and try out the ski on the water.
If that fixed it, then take the intake manifold off and fix the problem with the second pulse fitting.

Hey again.. got pulse from both lines.. other i can check? can it be my one way valve, because just find out there is not fitted any one way tank valve...

 

[Matt_E]

That's also a problem. Make sure you have a working one way valve on the tank.

 

[Sospikey]

I'd say thats a big problem. Get a valve right away! What's the compression? Is it hard to start?